Simple method to calculate cement quantity required for slab

Since concrete is the most used building material, cement which acts as a binder is one of the most important building elements which has cost implications if not well optimized. You may want to do a check of the cement quantity for your building project. Kindly follow the process below in this case:


Slab area= 180 square meters

Slab thickness= 150mm (6 inches)

Lenght of beam = 130 meters


Floor slab cement calculation

Number of bags of cement required= Volume of concrete x number of bags per cubic meters

Number of bags per cubic meter varies between 4 and 7 depending on the target mix strength

1:2:4 mix= approx 7 bags of cement per cubic meter

1:3:6 mix= approx 4 bags of cement per cubic meter

5 bags of cement per cubic meter is optimal considering cost and quality

Volume of slab= Slab Area x Slab thickness

Slab area= 180 sq.m

Thickness used= 150mm

Volume of slab= 180 x .15m


Beams and slabs are mostly casted together, hence:

Volume of beams= Total length of beams x width of beam x Height of beam

=130m x 0.225m x 0.3m= 8.8 m3

Total volume= 35.8 cubic meters

Cement bags required= 35.8 cubic meters x 5 bags per cubic meter

= 179 bags of cement


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  1. Favour

    35.8 x 1.7= 60.86
    So the above is wrong.

    • nighouseplans

      Thanks for the observation favour, It’s been updated.

  2. Ukpeowe John

    Nice one here.

    How do you now determine the sand components for same quantity of cement.

    • nighouseplans

      Dear Ukpe, Multiply the volume to be casted by a factor of 1.7.
      This gives 35.8×1.7= 60.86 tonnes of sand.

  3. Eugine

    This is so difficult

    • nighouseplans

      Dear Eugine, it’s not difficult once you can derive the volume and multiply by the required factor.

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